Collapsible form for concrete tanks



Oct. 8, 1963 w. J. STOVALL COLLAPSIBLE FORM FOR CONCRETE TANKS 3Sheets-Sheet 2 Filed June 1, 1962 William J. Stova/I 1N VEN TOR.

Oct. 8, 1963 w. J. sToVALL COLLAPSIBLE FORM FOR CONCRETE TANKS 3Sheets-Sheet 3 Filed June 1, 1962 William J Stoval/ INVENTOR.

United States Patent 3 106,007 CDLLAPSIBLE FORM FGR CGNCREIE TANKSWilliam J. Stovall, Rte. 2, Box 9%, Silsbee, Tex. Filed lane 1, 1962,Ser. No. 2%,146 6 Claims. (Cl. 25-130) This invention comprises a noveland useful collapsible form for concrete tanks and more particularlyrelates to a device which will enable the construction of cylindricaltanks of concrete especially adapted for use as cisterns or septictanks.

This application is a continuation-in-part of my prior co-pendingallowed application Serial No. 808,070, filed April 22, 1959 of the sametitle and which is now abandoned.

Primary object of this invention is to provide a collapsible form bywhich cylindrical tanks of the open top monolithic type may be readilyconstructed.

A further object of the invention is to provide a form for makingcylindrical tanks which shall be capable of quick assembly into positionfor receiving the cementitious material for forming a concrete tank andmay be easily collapsed and stored into a very compact volume.

A further object of the invention is to provide a collapsible formhaving improved means for supporting, securing and retaining cylindricalinner and outer walls in properly spaced position for receivingtherebetween the concrete material to form the wall of a concrete tank.

A further and more specific object of this invention is to provide alightweight, relatively inexpensive collapsible form for constructingconcrete tanks of the monolithic type having a cylindrical side wallwith a bottom wall and an open top and which form may employ arelatively lightweight sheet material with means for imparting thenecessary rigidity thereto in the assembled condition of the form.

Still another purpose of the unit is to provide a collapsible moldespecially suitable for the fabrication of monolithic cylindricalconcrete tanks of the open top type and which mold shall include pliablesheets comprising the inner and outer mold wall together with means todetachably but rigidly secure the upper and lower ends of said walls insecure and fixed relation whereby to precisely control the thickness anddiameter of the top and bottom portions of the concrete tank walls.

Yet another object of the invention is the provision of a collapsibleform which will enable a concrete tank to be formed in an invertedposition therein.

These together with other objects and advantagesrwhich will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

FIGURE 1 is a perspective view showing the collapsible form inaccordancewith this invention in its assemblecl or erected position inreadiness for forming a concrete tank therewith, part of thecementitious material being shown broken away;

FIGURE 2 is a top plan view of the arrangement of FIGURE 1 but showingthe form filled with concrete for forming a tank, and with a portion ofthe top of the form being broken away to show certain internal detailsthereof;

FIGURE 3 is a horizontal sectional view taken substantially upon thesection line. 3-3 of FIGURE 1 and showing a means for securing the innerwall of the form in fixed position relative to the outer wall and uponthe base of the form;

FIGURE 4 is a vertical transverse sectional view taken substantiallyupon the plane indicated by the section line 44 of FIGURE 1;

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FIGURE 5 is a perspective view of a key or locking means by which innerand outer wallsof the form are secured in fixed relation to each otherat their upper ends;

FIGURE 6 is a detail view in perspective showing the manner in which theends of the outer wall of the form are detachably joined to form asingle cylindrical outer wall member of the form;

FIGURE 7 is a detail view in vertical section through a portion of thestructure of an inverted tank as formed by the invention;

FIGURE 8 is a perspective view of a locking means by which the two endsof the cylindrical inner wall of the form are detachably securedtogether; and,

FIGURE 9 is a detail view taken in vertical section upon an enlargedscale and substantially upon the plane indicated by the section line 9-9of FIGURE 1.

It is the basic and fundamental purpose of this invention to provide areadily collapsible molding form which may be quickly and easilyassembled into its operative position and by means of which monolithiccylindrical open top concrete tanks particularly adapted for use ascisterns or septic tanks and the like may be quickly and easily formedin an inverted position and may be readily removed from the form whenthe concrete material has hardened therein.

In accordance with this invention the collapsible concrete formindicated generally by the numeral 10 includes a base which mayconveniently comprise a rigid fiat circular plate'or disk 12;. Rigidlysecured to this disk as by welding or in any other suitable manner arearcuate platelike abutment or stop members disposed in two concentricrows. These include an outer row 14 together with an inner row 16, theinner row, however, having one member 17, see FIGURE 3, which is movablysecured and mounted upon the base 12. For this purpose, the member 17 atone extremity thereof is secured to the base by a bolt 19, and adjacentits other end has secured thereto a laterally and radially inwardlyprojecting lug 21. A lever arm 23 is pivotally secured to the base 12 asby a pivot bolt 25 and has a short arm 27 constituting a cam elementwhich is adapted to abut against the element 17 and swing the latterabout its pivot pin 19 into the circular arrangement of the innermembers 16. The

' other end of the lever 23 is provided with a cable or other actuatingmeans 29, extending through a suitable opening inthe base 12, by whichrotation or pivoting movement may be imparted to the lever 23, as willbe seen by a comparison of the solid line and dotted line showings inFIGURE 3.

The inner and outer members 16 and 14 have disposed therebetween thelower ends of the cylindrical side walls 18 and 2a of the mold form. Thelower ends of the side walls rest upon the plate of the base 12 and bearagainst the opposed or adjacent vertical surfaces of the stop orabutment members 16 and 14 respectively, being retained therebetween bythe weight or pressure of the cementitious material or concrete 3t asset forth hereinafter. It will be observed from FIGURE 4 that the upperends of the inner and outer walls 20 and 18' are of different lengths,the upper edge of the member 18 extending upwardly beyond the upper edgeof the member 20. a

The inner and outer walls 2d and is each comprise a thin sheet of metalwhich is capable of readily flexing or bending. The material selectedpossesses the very desirable advantages of lightness of weight forhandling or transportation, ease of bending to facilitate compact pack.-aging, storing or shaping into its final contour in assembling the moldform. It has the disadvantage, however, in that it lacks sufiicientrigidity in itself to secure concrete tank [walls of sufficientlyuniform thickness. This last-mentioned disadvantage is effectivelyovercome, while all of the previously enumerated advantages are retainedby providing rigid spacing and retaining means at the upper and lowerends of the walls to obtain a fixed spaced relation therebetween.

Although the weight and pressure of the concrete material may result insome outward deflection of the inner and outer walls between the upperand lower ends, re-' sulting in a non-uniform but increased wallthickness of the concrete tank wall, this condition is not objectionablesince the relatively rigid mounting and uniform spacing of the mold formwalls 18 and 2d at their top and bottom edges will obtain the verydesirable condition of a uniform and precisely controlled thickness ofthe concrete wall thickness at its top and bottom.

Lateral movement of the bottom edges of the walls 18 and 20 away fromeach other, under the pressure of the concrete material 3%, is limitedby their engagement with the fixed stop or abutment members 16 and 14.The upper ends are secured in fixed relation to each other by detachablefasteners or keys 22, see FIGURE 5, which each consists of a flat rigidplate-like body having a pair of parallel notches therein. A relativelyshallow notch 24 is adapted to receive the upper end of the inner wall29, while a relatively deep notch 26 embraces and receives therein theouter wall 18, as shown clearly in FIGURE 4. Thus, by the provision of aplurality of these fasteners 22, which may be individually placedwherever desired about the edges, the upper ends of the concentric wallsof the form are quickly and rigidly connected to each other to providean annular space therebetween. This permits correction to be made whenthe thin sheet metal walls are out of round.

The concrete material is poured or packed between the two walls 18 and20 as shown at 3% from the top of the mold and constitutes thecylindrical wall of the tank to be formed or created by this form.

The outer wall 18 preferably consists of a single sheet of metal whichis bent upon itself and its ends provided with vertical angle members 32and 34 fixedly secured thereto as by welding or the like. Suitablefasteners 36 connect these angle members together and thus rigidlysecure the sheet in a circular or cylindrical formation to form theouter wall of the tank.

The inner wall 20 likewise consists of a sheet of pliable or flexiblematerial, which has its adjacent vertical edges provided with aplurality of vertically spaced and aligned sections of pipes or sleeves38 welded or otherwise secured thereto. These sleeves are interdigitatedas shown in FIGURE 4 so when the edges of the sheet 20 are broughttogether, the sleeves or pipe sections Will be in vertical alignment inorder that a fastening means in the form of a pin 4%, see FIGURE 8, maybe inserted therein to thus retain the edges together and the sheet ofmaterial in a cylindrical form to form the inner wall of the form.

As so far described it will now be apparent that the base 12 may be laidin any suitable position upon the ground, and the inner and outersleeves 20 and 18 may then be each secured together at its ends to forma cylindrical closed wall and positioned between the abutment elements16 and 14, thus firmly securing against l-atenal separation the lowerends of the inner and outer walls of the form. The upper ends aresecured fixedly to gether in spaced relation to each other by the platesor fasteners 22 as previously mentioned.

It will now be observed from FIGURE 4 that at the upper edge of theinner wall 20 there are provided a plurality of L-shaped brackets whichare Welded or otherwise fixedly secured to what may be termed the insidesurface of the wall 20. Each bracket, which is designated generally bythe numeral 42 includes a vertical flange 44 which is welded to theinside surface of the inner wall 20 at the top edge of the same,together with a horizontal flange 46 whose top surface is disposed atthe upper edge of the inner wall 2% and extends radially inwardly of thewall Zil. The series of brackets 42 constitute support means whose topsurfaces support a rigid metal plate or disk 43 which rests upon the topof the bracket flanges 46 and which plate has its top surface positionedto support the mass of concrete 5t} which will constitute the bottomWall of the tank. This material 5'0 is filled into the space bounded bythe upper edge of the outer wall 18 and the plate 43, and bonds with theconcrete material 36 of the wall of the tank between the fasteners 22.

In the arrangement shown in FIGURE 4 the brackets 42 are shown as beingdownwardly displaced from the top edge of the inner mold Wall 2% so thatthe top surface of the plate 48 will be flush with the upper edge of theinner wall.

While the arrangement of brackets shown in FIGURE 4 is satisfactory forsome uses of the invention, the arrangement shown in FIGURE 9 isgenerally preferred. Here the top surfaces of the horizontal flanges 46are flush with the top edge of the inner wall 26-, whereby the bottomsurface of the plate 48 will be flush with the inner wall upper edge.This prevents the positioning of any concrete within the inner wall,thus facilitating collapsing of the inner wall and its removal from themolded concrete tank.

Referring now to FIGURE 7 it will now be understood that after theconcrete material for the wall and bottom of the tank has been poured asat 30 and 50 and has partially set for some little time but is not yetcompletely hardened, the fasteners 22 may be removed. This Will leavegenerally rectangular shaped and vertically extending slots in theconcrete material 54 and 3% as shown at 52. These slots may be filled asindicated at 53 in FIG- URE 7 by fresh cement being applied thereto andtroweled or smoothed in place.

After the cement material has hardened the fasteners 36 may be removedand the outer wall 18 may then be stripped from the form. The form maythen be turned so that the concrete tank rests upon its bottom wall 50,thereafter, the lever 23 will be released so that the member 17 may moveinwardly and the base 12; may then be stripped from the side wall 36 andthe fastener 46 may then be removed andthe inner wall 20 may be radiallycontracted upon releasing the locking means 29, 23, 27, 21 and thenremoved. The concrete tank is then ready for use and the form is readyto be cleaned reassembled and again used.

In some instances, tar paper or other waterproof material may be placedover the plate 48 when the latter is placed in the form upon thebrackets 42 to prevent the concrete adhering thereto to facilitateremoving of this plate after the concrete has set and hardened into thecomplete tank.

-It will be further understood that in some instances it may bepreferred to form the base 12 as an annulus or ring rather than as asolid disk both to lighten the weight of the same and to also facilitateentry into the interior of the form as for example in order to apply orremove the fastener 4i and also have access to the lever 23 and itsactuating cable 29 by means of which the movable stop or abutment member17 is locked into proper position for holding the inner wall in placeand for being moved to a position to release the same and permit easyremoval of the inner wall.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention asclaimed.

What is claimed as new is as follows:

1. A collapsible form for making concrete tanks comprising a base and apair of concentric inner and outer walls mounted upon said base at theirlower edges, circumferentially spaced upstanding means on said basemaintaining the lower ends of said walls in fixed spaced relation uponsaid base, fasteners securing the upper edges of said walls in fixedspaced relation whereby they may receive and retain therebetweenconcrete to form the wall of a tank, a plate disposed on the inner walland below the upper end of the outer wall and cooperating with thelatter to support concrete to -form the bottom of a tank, support meanscarried by said inner wall for mounting said plate, said maintainingmeans comprising inner and outer abutment elements consisting of arcuateblocks fixedly mounted on and projecting upwardly from said base inconcentric circles, the lower edges of said walls being received betweensaid inner and outer abutment elements and being engaged and preventedfrom separation thereby, the blocks of the inner circle including anarcuate element pivoted to said base, a lever pivoted to said base, andhaving a cam surface engaging said arcuate element for releasablylocking the latter into retaining engagement with said inner wall.

2. The combination of claim 1 wherein said fasteners each consist of avertically extending rigid plate having a pair of notches projectingupwardly from its lower edge, the notches being of different verticalextent with the top edges of said inner and outer walls being receivedrespectively in the shallower and deeper of said notches respectively,said fasteners having vertical edges disposed inwardly of said innerwall and engaging the periphery of said plate for positioning the lattercentrally of said inner wall.

3. The combination of claim 1 wherein said fasteners comprise a seriesof manually engageable locking keys individually positionable upon saidinner and outer walls at selective circumferentially spaced positionsthereon, each key comprising a rigid, vertically extending metallicplate, said plate having a lower edge with a pair of notches extendingupwardly from! said lower edge to different vertical heights in saidplate whereby to seat and rigidly,

retain in fixed spaced relation the adjacent portions of the upper edgesof said inner and outer walls.

4. The combination of claim 1 wherein each wall consists of a singlepiece of a pliable and readily bendable sheet metal whereby it may beeasily collapsed and compactly folded for storage, said base plate andfasteners being of a rigid material whereby to stiffen said sheet metalin their assembled relation and maintain the upper and lower edges ofthe sheets in fixed relation to each other and against inward collapse.

5. A collapsible form for making concrete tanks comprising a base and apair of concentric inner and outer walls mounted upon said base at theirlower edges, circumferentially spaced upstanding means on said basemaintaining the lower ends of said walls in fixed spaced relation uponsaid base, fasteners securing the upper edges of said walls in fixedspaced relation whereby they may receive and retain therebetweenconcrete to form the wall of a tank, a plate disposed on the inner walland below the upper end of the outer wall and cooperating with thelatter to support concrete to form the bottom of a tank, support meanscarried by said inner wall for mounting said plate, said maintainingmeans comprising inner and outer abutment elements consisting of arcuateblocks fixedly mounted on and projecting upwardly from said base inconcentric circles, the lower edges of said walls being received betweensaid inner and outer abutment elements and being engaged and preventedfrom separation thereby, the blocks of the inner circle including anarcuate element pivoted to said base, means movably mounted on said baseand engaging said arcuate element for releasably locking the latter intoretaining engagement with said inner wall.

6. The combination of claim 5 wherein said support means include aplurality of circumferentially spaced support brackets secured to andprojecting inwardly from the inner wall adjacent its upper edge, saidplate being rigid and being carried by the inner wall at its upper edge,said brackets constituting both a support for said plate and a stiffenerfor said inner wall, said plate having its periphery engageable withsaid iasteners whereby said plate will prevent inward collapse of theupper ends of said walls.

References Cited in the file of this patent UNITED STATES PATENTS386,979 Haase July 31, 1888 1,125,221 Venable Jan. 19, 1915 2,786,252Curran Mar. 26, 1957 2,894,311 Sinclair .July 14, 1959

5. A COLLAPSIBLE FORM OF MAKING CONCRETE TANKS COMPRISING A BASE AND A PAIR OF CONCENTRIC INNER AND OUTER WALLS MOUNTED UPON SAID BASE AT THEIR LOWER EDGES, CIRCUMFERENTIALLY SPACED UPSTANDING MEANS ON SAID BASE MAINTAINING THE LOWER ENDS OF SAID WALLS IN FIXED SPACED RELATION UPON SAID BASE, FASTENERS SECURING THE UPPER EDGES OF SAID WALLS IN FIXED SPACED RELATION WHEREBY THEY MAY RECEIVE AND RETAIN THEREBETWEEN CONCRETE TO FORM THE WALL OF A TANK, A PLATE DISPOSED ON THE INNER WALL AND BELOW THE UPPER END OF THE OUTER WALL AND COOPERATING WITH THE LATTER TO SUPPORT CONCRETE TO FORM THE BOTTOM OF A TANK, SUPPORT MEANS CARRIED BY SAID INNER WALL FOR MOUNTING SAID PLATE, SAID MAINTAINING MEANS COMPRISING INNER AND OUTER ABUTMENT ELEMENTS CONSISTING OF ARCUATE BLOCKS FIXEDLY MOUNTED ON AND PROJECTING UPWARDLY FROM SAID BASE IN CONCENTRIC CIRCLES, THE LOWER EDGES OF SAID WALLS BEING RECEIVED BETWEEN SAID INNER AND OUTER ABUTMENT ELEMENTS AND BEING ENGAGED AND PREVENTED FRON SEPARATION THEREBY, THE BLOCKS OF THE INNER CIRCLE INCLUDING AN ARCUATE ELEMENT PIVOTED TO SAID BASE, MEANS MOVABLY MOUNTED ON SAID BASE AND ENGAGING SAID ARCUATE ELEMENT FOR RELEASABLY LOCKING THE LATTER INTO RETAINING ENGAGEMENT WITH SAID INNER WALL. 